This project is intended to test a method for measuring the disclosure of stressful emergent life events within psychotherapy encounters as well as therapy providers' responses to those disclosures. Our preliminary data suggest that such events are frequent and unpredictable and that they interfere with providers' ability to follow an evidence-based session plan. Our pilot studies also show that these events are associated with a significantly worse rate of clinical improvement. We therefore propose to measure these events with a high level of precision using an extensive coding system with digital recordings samples from an archive of over 1,200 psychotherapy sessions with children and adolescents treated in community mental health settings in a recent randomized effectiveness trial. We then plan to test whether and how these events significantly impact providers' ability to adhere to their therapy plan, and whether selected aspects of the treatment program (e.g., suitability to address the stressor), the person reporting the event (e.g., timing o emotionality of the disclosure), or the events themselves (e.g., content, severity) influence the nature and degree of the provider response. The project will yield two specific products: (1) reliable instrumentation to code emergent life events in any digital psychotherapy recordings, which will be employed in this proposal, but could be used in nearly any future proposal investigating this important phenomenon (e.g., moderator analyses in studies of clinical outcomes with nearly any treatment model) and (2) a detailed set of findings from the planned research that can inform the subsequent development of an algorithm for providers to anticipate, address, and manage disclosures of such events in a supportive and constructive manner. Such an approach would ideally allow the provider to make appropriate use of the planned evidence-based treatment content to the fullest extent possible. This work is intended to serve the larger mission of NIMH by increasing the potential for scientifically developed mental health interventions to be applied successfully in everyday clinical contexts. By understanding the nature and impact of unanticipated, real-time threats, we hope to inform subsequent practice models that would increase the chance that mental health service providers can stay on plan in the face of common challenges. Such knowledge and the strategies they ultimately produce can directly preserve and enhance the public health impact of evidence-based treatments. In addition, this improved understanding ultimately has the potential to lead to increased provider satisfaction and provider ratings of the feasibility of evidence-based protocols in their actual clinical circumstances, as we better understand how to make treatments more immediately responsive while preserving the core features that make them effective.